In general, a thin-film solar cell module includes a transparent electrode, a semiconductor layer, and a metal electrode which are sequentially formed on a transparent substrate.
For example, when a semiconductor layer is formed on a transparent electrode by the CVD method, a foreign material attached onto the transparent electrode may be incorporated into the semiconductor layer, in some cases. When a pinhole is formed by separating such a foreign material from the semiconductor layer, and is filled with a material of a metal electrode, a short circuit occurs between the transparent electrode and the metal electrode. This results in a problem that the output of the solar cell module is reduced.
Then, a technique is proposed in which a material of a metal electrode filled into a pinhole is vaporized by application of a voltage (hereinafter referred to as a “reverse voltage”) in a direction opposite to the direction of a photo-electromotive force to be generated in a semiconductor layer (refer to, for example, Patent Document 1). The step of applying a reverse voltage is generally called a “reverse voltage repair process”.